You can make a Homemade Dishwasher Detergent using some of the same ingredients you purchased to make your Laundry Detergent. In addition to Washing Soda and Borax you will also need Kosher Salt and Citric Acid.
Here is the Recipe that I use:
1 Cup Borax
1 Cup Washing Soda
1/2 Cup Kosher salt
1/2 Cup Citric Acid
There are several options you can use for the citric acid. It can be purchased in bulk online or you may try and find it in or around the pharmacy area of your grocery store. You could also ask your pharmacy to order it for you. Unless you are buying a lot though it can be kind of pricey. There are also a couple of other options you can use for the citric acid that are very easy to find in your local grocery store.
1 - 15 packets of unsweetened Lemon Kool-Aid
2 - Lemi Shine
3 - Fruit-Fresh
Before I made the investment to buy a large bottle of citric acid I thought I would try out this recipe using some of these other items that I could buy in smaller quantities. The first batch of detergent I made I used 15 packets of unsweetened kool aid and it seemed to work okay, but I had a lot of caking occur so I ended up having to break it up with a butter knife. If I used this method again I might try to pack it into ice cube trays, allow it to cake together and then remove them so they are in individual squares. My 2nd batch of detergent I decided to try Lemi-shine. I used this product a lot when I lived in Utah to help remove the hard water spots from the glassware. It really works well and I had a bit left over so I decided to give it a try. So far I like the results I have gotten with the Lemi-shine much better. I have had very little caking and I also think the dishes are cleaner, I especially notice with the silverware. They were clean with the kool aid batch but a little filmy and I have noticed with the lemi-shine batch they are much shinier. I like the results of my efforts so I think the next step for me is to invest in a large bottle of citric acid or continue with the lemi-shine, whichever is the cheaper route.
As I was researching this and trying to find a recipe that I wanted to try I read a lot of stuff saying that homemade detergents aren't recommended for dishwashers because commercial detergents have chemicals added to keep your plumbing clear. This could be remedied however, by using a regular detergent every month or so to clean out build up and you can also make sure to use a good dishwasher cleaner every month or so as well. So far I have had good results from my homemade detergent. It seems to work well and it saves a ton of money!!!!
Rinse agents for the dishwasher are very expensive! I have learned that you can simply use white vinegar in place of your rinse agent. It works well and is so much cheaper. White vinegar also works great as a dishwasher cleaner. Just fill a glass measuring cup up with 1 Cup white vinegar place it upright in the bottom rack of your dishwasher and let your dishwasher run it's regular cycle. This really helps remove the hard water from your dishwasher.